fix(updater): only uses DoH to cloudflare+google

- prevent dns plaintext manipulation both the periodic update and when running in cli mode
- possibly higher reliability on poor connections versus UDP
- drop `-dns` flag in update command
- for now no configuration allowed since it makes everything rather complex

internal/updater/resolver/interfaces.go

@@ -0,0 +1,10 @@
+package resolver
+
+import (
+	"context"
+	"net"
+)
+
+type Dialer interface {
+	Dial(ctx context.Context, network, address string) (net.Conn, error)
+}